Field of the Invention
The invention relates to a microcircuit card containing multiple pre-cut cards containing a same global contact area.
Description of the Related Art
Various microcircuit card formats are known that have contact areas, some of which are defined in the standards ETSI 102 221 (including the latest version, V11.0.0 dated 2012 June) and IS07816. Thus, there are four known formats, known by the designations 1FF to 4FF:                the 1FF format, also called ID-1, corresponds to the format of credit cards and to a body delimited by a rectangular form of 85.6 mm×54 mm×0.76 mm,        the 2FF format, also called ID-000, the card body of which is delimited by a rectangular form of 15 mm×25 mm×0.76 mm, with a 3×3 mm foolproof feature in a corner of the card body, and        the 3FF format, also called Mini UICC, the card body of which is delimited by a rectangular form of 15 mm×12 mm×0.76 mm, with a 2.5×2.5 mm foolproof feature in a corner of the card body, and        the 4FF format, recently defined, the card body of which is delimited by a rectangular form of 12.3 mm×8.8 mm×0.67 mm with a 1.65 mm×1.65 mm foolproof feature.        
These cards have in common the fact that they comprise a microcircuit and individual contact areas or surfaces connected to the microcircuit; the contact surfaces are usually arranged so as to jointly form a global contact area, the outline of which is usually of simple geometrical form, often globally rectangular; conventionally, the microcircuit and the global contact area are borne by a wafer, on the respective faces thereof with which they form a module mounted in a cavity in the body that each card includes.
These contact areas are intended to allow the card concerned to communicate with a communication device by contact. In the case of the 1FF, 2FF or 3FF cards, this contact plate is generally provided with eight contact surfaces commonly designated by the references C1 to C8 usually distributed over two substantially parallel columns. A first column can comprise contacts called C1 to C4 and a second column can comprise the contacts called C5 to C8. The standard ISO7816-2 notably defines the minimum zones of these contact surfaces, namely 2 millimeters wide and 1.7 millimeters high. This standard also defines the relative positions of these contact zones and their dimensions.
Thus, the contact surfaces correspond to actual surfaces whereas the contact zones correspond to the minimum theoretical locations described by the standard ISO7816.
For information, the contact surfaces C1 and C5 are used for the power supply or C1, corresponds to Vcc, also called “positive power supply” and C5 corresponds to GND, also called “earth”.
The contact surface C2, also called RST, serves as chip reset.
The contact surface C3, also called CLK, serves as clock for the chip.
The contact surface C7, also called I/O, serves as inputs and outputs for chip information.
The contact surfaces C4, C6 and C8 are intended to be so-called “spare” contacts, which have no particular functions. These days, these contacts C4 and C8 can be used for the USB ports and the contact C6 can be used for the SWP (Single Wire Protocol) communication protocol.
Hereinafter in the description, it can be considered that the contacts that have an index between 1 and 8 have the same functions as those described above.
With regard to the most recent format, 4FF, which is also the smallest, provision is made for the contact surfaces C4 and C8 to be situated between the columns combining the contacts C1 to C3 (on the left) and the contacts C5 to C7 (on the right).
For the rest of the description, it will be considered that a microcircuit card, substantially rectangular with the front face (facing the observer) supporting the contact plate, has the foolproof feature at bottom right of this card. By extension, the face opposite the front face is the rear face.
Concerning the card of 4FF format, it can thus be stated that the contacts C1 and C5 are situated in proximity to the top (or upper) edge of the card or of the contact plate, that the contacts C3 and C7 are situated in proximity to the bottom (or lower) edge, that the contacts C1 to C3 are situated in proximity to the left edge and that the contacts C5 to C7 are situated in proximity to the right edge, that the contact C4 is situated in proximity to the top edge between the two columns and that the contact C8 is situated in proximity to the bottom edge between the two columns.
It should be noted that, although the standards specify the locations and dimensions of the contact zones C4 and C8, a card may not include any specific contact surface C4 or C8, if no function is used in relation to these contacts. In particular, there are cards of 4FF format, even of larger format, that comprise only six distinct contact surfaces, respectively intended to be in contact with contacts C1 to C3, C5 to C7 of an external communication device in read or write mode.
The tolerances of all the cards described above are of the order of 0.1 mm.
The variety of possible uses for a microcircuit card has led to the desire to be able to read a microcircuit in contact-based exchange devices suitable for receiving bodies of various formats; moreover, it has emerged as efficient, from the production point of view, to fabricate microcircuit cards having a given format, and by precutting therein smaller card bodies; in particular, it is still conventional practice to fabricate microcircuit cards in the 1FF format by pre-cutting therein a card body of 2FF format. More recently, it has also been proposed to pre-cut, in a card of 1FF format, a card body in the 2FF format by pre-cutting therein a body of 3FF format; these pre-cuts are made in such a way that the microcircuit mounted in the card of maximum format, in practice 1FF, observes the conditions concerning the placements of the contact surfaces associated with the 2FF format when the body of 2FF format is detached from the original card, even with the 3FF format when the body of 3FF format is detached.
To simplify the detachment of the desired body in a card produced in the 1FF format, the document FR-2 967 515 has proposed various additional cuts that mean that the detachment of the card body in the 3FF format is done by destroying the body in the 2FF format.
With the widening use of the 4FF format, it is now advantageous to be able to fabricate cards in which various card bodies are precut, including the body in the 4FF format, with a microcircuit that observes the dimensioning and placement conditions stipulated by the standards concerning this 4FF format.
However, there are applications in which it is desirable to be able to use a card body in the 4FF format in a contact-based communication device capable of receiving a card in the 4FF format and in another contact-based communication device intended to receive cards with a larger format; to satisfy such a need, adapters have been proposed suitable for receiving a card having a small format by having a larger format relative to which the contact surfaces of this card are positioned so as to observe the constraints of the standards relating to the contact surfaces of a card in the format of the adapter.
However, a difficulty is encountered with the cards of 4FF format whose width (measured parallel to the contact surface alignments, according to the convention mentioned above) is 8.8 mm, whereas the 3FF format defines a width of 12 mm; if the contact zones provided by the standards applicable to the 4FF format are superimposed with those provided by the standards that apply to the 3FF format, it is found that the 3FF format overruns by scarcely 330 micrometers along the top edge of these formats (but by 2.87 mm along the bottom edge); that means that the adapter that makes it possible to convert a card in the 4FF format to the 3FF format is formed by a frame (having, or not having, a bottom), the top side of which has a width of scarcely 330 micrometers, which amounts to stating that this adapter exhibits high risks of breaking this top side in its use.
To mitigate this drawback, there has been proposed, in the document FR-2 982 690 (or the document WO-2013/072616), an adapter in the 3FF format suitable for receiving a card of smaller format, for example in the 4FF format, this small card having contact surfaces which are modified so as to allow the adapter to have a top side that has sufficient width to give it a mechanical strength compatible with its use as adapter.
This modification of the contact surfaces consists in practice in offsetting the contact surfaces of the card in the 4FF format toward its top edge. This offset is identical for all the surfaces C1 to C7 and leads to a reduction of the contact surface C1 (or C5) and an increase in the contact surface C3 (or C7), by reducing the distance between the top edge of the contact zone provided by the standards and the top edge of the card body in the 4FF format, which then makes it possible to increase the width of the top side of the adapter in the 3FF format.
Such a modification therefore amounts to abandoning the usual design rules for the contact plates of microcircuit cards. More specifically, the contact surfaces are arranged in such a way as to encompass the theoretical contact zones provided by the standards to guarantee that a good contact is established with the bump contacts of a contact-based communication device intended to receive a card equipped with such contact surfaces; to optimize such a contact, each contact surface is defined with the greatest possible surface area to guarantee a good contact with the bump contacts of such a communication device despite the fabrication tolerances; that is reflected by the fact that the outlines of the individual contact surfaces are defined relative to one another in such a way as to be separated only by limited spaces with the result that, in appearance, the global contact areas occupy practically all the surface situated within the outline of the global contact area; the almost continuous appearance of the global contact area leads to this area being likened in practice to a plate and to the notion of contact plate. In other words, the individual contact surfaces are in practice globally centered on the theoretical contact zones provided by the standards by exceeding the latter as much as possible while being effectively electrically insulated from one another.
Now, the standards set, for the theoretical contact zones of the various formats of microcircuit cards with contact areas, a regular distribution, which leads to the choice, for the contact surfaces, of a distribution that is also regular, with, in practice, a symmetry relative to a median line extending lengthwise in the body of the card concerned; in the case of a card of 4FF format, it is thus sought to arrange the contact surfaces C1 and C3 (respectively C5 and C7) symmetrically relative to a median line of the body passing through the middle of the contact surface C2 (respectively C6). Similarly, it is usually sought to arrange the surfaces C1 to C3 in a column which is substantially symmetrical to the column formed by the surfaces C5 to C7 (it being stipulated that, in practice, when no specific surface of C4 or C8 type is provided, it is usual practice for the contact surface C5 to be prolonged toward the column C1-C3 then downward so as to occupy the space situated between these columns; this in practice results in a mechanical strengthening because of the presence of the conductive material forming the contact surfaces while conferring a certain esthetic on the contact area formed by the set of contact surfaces. Moreover, it will be understood that the mechanical strength of a card having a small format such as the 4FF format is all the better when the module that it contains is arranged centrally relative to its outline, which amounts to stating that it is desirable for the contact area to be centered relative to the outline of the card body, at least in the direction of its smaller dimension (that is to say its width, measured vertically according to the convention defined above).
The object of the invention is to simultaneously satisfy the two objectives mentioned above, namely to make it possible to fabricate a card comprising a microcircuit surrounded by at least one pre-cut in the 4FF format and one pre-cut in the 3FF format, while making it possible for the material situated between these pre-cuts to constitute an adapter making it possible, without inadvertently breaking, to convert the card in the 4FF format to the 3FF format while retaining as far as possible the design rules for the contact surfaces.
It will be understood that such a problem arises when there is a card whose format is at least equal to the 2FF format, but that the invention has a quite particular benefit when the format of the card is 1FF, in which it is possible to effectively produce a very large number of cards.